Question: The function $f : \mathbb{R} \to \mathbb{R}$ satisfies
\[f(x) + 2f(1 - x) = 3x^2\]for all $x.$  Find $f(4).$
Explanation: Setting $x = 4$ in the given functional equation, we get
\[f(4) + 2f(-3) = 48.\]Setting $x = -3$ in the given functional equation, we get
\[f(-3) + 2f(4) = 27.\]Doubling the second equation, we get $2f(-3) + 4f(4) = 54.$  Subtracting the equation $f(4) + 2f(-3) = 48,$ we get $3f(4) = 6,$ so $f(4) = \boxed{2}.$